Override an admin controller in Magento 2

[dbsdsun]

This post walks through the process to override an admin controller in Magento 2. Code is available at https://github.com/dbsdsun/magento2Override.

There are a few steps to override a Magento 2 controller.

1. Building a Magento 2 extension structure
2. Setting preference in di.xml
3. Defining an overriding controller class

Step 1. Building a Magento 2 extension structure

Building directories as following:

magento2 --- app --- code
                       |--- Sample --- HelloWorld
                       | --- Controller
                       | --- etc
                              | --- module.xml
                              | --- di.xml

Creating module.xml to define a Magento2 extension:

<?xml version="1.0"?>
<!--
/**
 * Created by wilson.sun330@gmail.com
 * Date: 11/09/2015
 * Time: 5:02 PM
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/Module/etc/module.xsd">
    <module name="Sample_HelloWorld" setup_version="0.0.1"/>
</config>

Step 2. Setting preference in di.xml

Creating di.xml to refer the overriding class:

<?xml version="1.0"?>
<!--
/**
 * Created by wilson.sun330@gmail.com
 * Date: 11/09/2015
* Time: 5:02 PM
*/
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/ObjectManager/etc/config.xsd">
<preference for="Magento\Catalog\Controller\Adminhtml\Product\Edit" type="Sample\HelloWorld\Controller\Catalog\Adminhtml\Product\Edit" /> 
</config>

Sample\HelloWorld\Controller\Catalog\Adminhtml\Product\Edit will be used to override Magento\Catalog\Controller\Adminhtml\Product\Edit, which is the product edit controller for admin in original Magento 2.

Step 3. Defining an overriding controller class

Under magento2/app/code/Sample/HelloWorld/Controller/Catalog/Adminhtml/Product, defining Edit.php as following.

<?php
/**
 * Created by wilson.sun330@gmail.com
 * Date: 11/09/2015
 * Time: 5:02 PM
 */
namespace Sample\HelloWorld\Controller\Catalog\Adminhtml\Product;

class Edit extends \Magento\Catalog\Controller\Adminhtml\Product\Edit
{
 public function execute()
 {
 $this->messageManager->addSuccess('Message from new admin controller.');
 return parent::execute();
 }
} 

Edit.php redefines function execute() to override the function in \Magento\Cms\Controller\Adminhtml\Product\Edit. The new execute() adds a message to product edit page, but it may also implements a complex logic.